Handling a fault in an ethernet ring network

Abstract

The present disclosure relates to a fault handling method for a communication network that comprises a plurality of intersecting Ethernet rings including at least a first Ethernet ring having a first master node and a first transit node and a second Ethernet ring having a second master node and a second transit node, the first Ethernet ring and the second Ethernet ring intersecting at a first shared link connecting at least a first shared node and a second shared node shared between the first Ethernet ring and the second Ethernet ring, the method comprising a ring-extension process including the second master node joining the first Ethernet ring as a transit node upon determination of a fault in the first shared link, and the second master node sending a RING EXTEND message to notify the second transit node to join the first Ethernet ring as a transit node of the first Ethernet ring.

1 . A fault handling method for a communication network that comprises a plurality of intersecting Ethernet rings including at least a first Ethernet ring having a first master node and a first transit node and a second Ethernet ring having a second master node and a second transit node, the first Ethernet ring and the second Ethernet ring intersecting at a first shared link connecting at least a first shared node and a second shared node shared between the first Ethernet ring and the second Ethernet ring, the method comprising:
 a ring-extension process comprising:
 the second master node joining the first Ethernet ring as a transit node upon determination of a fault in the first shared link; and 
 the second master node sending a RING EXTEND message to notify the second transit node to join the first Ethernet ring as a transit node of the first Ethernet ring. 
   
     
     
         2 . The method of  claim 1 , wherein
 the ring-extension process further comprises:
 the first shared node sending a SHARED LINK DOWN message upon detection of the fault in the first shared link, wherein the second master node determines the fault in the first shared link by receiving the SHARED LINK DOWN message. 
   
     
     
         3 . The method of  claim 1 , wherein the second master node has a primary port and a secondary port, and wherein each of the first and second Ethernet rings are identified by a ring sequence number, the ring sequence number of the first Ethernet ring being lower than the ring sequence number of the second Ethernet ring, and each of the first and second Ethernet rings forming a respective ring network identified by a respective network ID, and wherein
 the ring-extension process further comprises:
 the first shared node sending a SHARED LINK DOWN message upon detection of the fault in the first shared link, wherein the second master node determines the fault in the first shared link by receiving the SHARED LINK DOWN message, and wherein the second master node joining the first Ethernet ring as a transit node comprises: 
 the second master node creating first correspondence information between the network ID of the second Ethernet ring and the ring sequence number of the first Ethernet ring contained in the received SHARED LINK DOWN message; and 
 the second master node creating second correspondence information between the primary port and the secondary port of the second master node and the ring sequence number of the first Ethernet ring contained in the received SHARED LINK DOWN message. 
   
     
     
         4 . The method of  claim 1 , wherein each of the first and second Ethernet rings is identified by a ring sequence number, the ring sequence number of the first Ethernet ring being lower than the ring sequence number of the second Ethernet ring, and wherein the ring-extension process further comprises:
 the first shared node sending a SHARED LINK DOWN message upon detection of the fault in the first shared link, wherein the second master node determines the fault in the first shared link by receiving the SHARED LINK DOWN message;   the second transit node receiving the SHARED LINK DOWN message from the first shared node and the RING EXTEND message from the second master node; and   the second transit node joining the first Ethernet ring as a transit node of the first Ethernet ring upon receiving the RING EXTEND message by creating correspondence information between a port at which the RING EXTEND message is received by the second transit node and a port at which the SHARED LINK DOWN message is received by the second transit node, and the ring sequence number of the first Ethernet ring contained in the received RING EXTEND message and SHARED LINK DOWN message.   
     
     
         5 . The method of  claim 1 , wherein each of the first and second Ethernet rings is identified by a ring sequence number, the ring sequence number of the first Ethernet ring being lower than the ring sequence number of the second Ethernet ring, and wherein
 the ring-extension process further comprises:
 the first shared node sending a SHARED LINK DOWN message upon detection of the fault in the first shared link, wherein the second master node determines the fault in the first shared link by receiving the SHARED LINK DOWN message; 
 the first shared node receiving a RING EXTEND message from the second master node and causing the sending of the SHARED LINK DOWN message to stop; 
 the first shared node creating correspondence information between a port at which the RING EXTEND message is received by the first shared node and the ring sequence number of the first Ethernet ring based on the received RING EXTEND message; and 
 the second master node causing the sending of a RING EXTEND message to stop when no SHARED LINK DOWN message is received within a predetermined interval. 
   
     
     
         6 . The method of  claim 1  further comprising:
 a ring-recovery process, including:
 the second master node determining that the first shared link is restored and leaving the first Ethernet ring; and 
 the second master node notifying the second transit node to leave the first Ethernet ring. 
 
 
     
     
         7 . The method of  claim 6 , wherein
 the ring-recovery process further comprises:
 the first shared node receiving a SHARED LINK HELLO message from the first shared link and determining that the first shared link is restored; and 
 the first shared node sending a SHARED LINK UP message to notify the second master node that the first shared link is restored, 
 wherein the second master node determines that the first shared link is restored when the second master node receives the SHARED LINK UP message. 
   
     
     
         8 . The method of  claim 6 , wherein the first shared node has an extension port that connects to the second Ethernet ring, and wherein
 the ring-recovery process further comprises:
 the first shared node receiving a SHARED LINK HELLO message from the first shared link and determining that the first shared link is restored; 
 the first shared node sending a SHARED LINK UP message to notify the second master node that the first shared link is restored and blocking the extension port from sending data to or receiving data from the second Ethernet ring; 
 the second master node sending a COMPLETE-FLUSH FDB message upon receiving the SHARED LINK UP message; and 
 the first shared node unblocking the extension port upon receiving the COMPLETE-FLUSH FDB message. 
   
     
     
         9 . The method of  claim 6 , wherein the second master node has a primary port and a secondary port that is blocked from receiving data, and the first shared node has an extension port that connects to the second Ethernet ring, and wherein
 the ring-extension process further comprises:
 the second master node unblocking the secondary port to allow data to be received at the secondary port, and wherein 
   the ring-recovery process further comprises:
 the first shared node receiving a SHARED LINK HELLO message from the first shared link and determining that the first shared link is restored; 
 the first shared node sending a SHARED LINK UP message to notify the second master node that the first shared link is restored and blocking the extension port from sending data to or receiving data from the second Ethernet ring; 
 the second master node blocking the secondary port upon receiving the SHARED LINK UP message and sending a COMPLETE-FLUSH FDB message; 
 the first shared port unblocking the extension port upon receiving the COMPLETE-FLUSH FDB message; and 
 the second transit node leaving the first Ethernet ring upon receiving the COMPLETE-FLUSH FDB message. 
   
     
     
         10 . The method of  claim 1 , wherein each of the plurality of Ethernet rings has a respective master node and at least one transit node, and each Ethernet ring intersects a neighbouring Ethernet ring at a respective shared link connecting at least two shared nodes shared between the two intersecting Ethernet rings, and wherein each Ethernet ring is identified by a ring sequence number, the first Ethernet ring being identified by a first ring sequence number that is the lowest ring sequence number amongst the plurality of Ethernet rings, and the second Ethernet ring being identified by a second ring sequence number that is higher than the first ring sequence number, the method further comprising:
 a set-up process including:
 recording first correspondence information between the ports of the first master node and the first transit node, and the first ring sequence number; and 
 recording second correspondence information between the ports of the second master node and the second transit node, and the second ring sequence number, and between the ports of the second master node and the second transit node, and the ring sequence number of each Ethernet ring amongst the plurality of Ethernet rings having a ring sequence number lower than the second ring sequence number. 
   
     
     
         11 . The method of  claim 10 , wherein
 in the ring-extension process:
 the second master node and the second transit node join the first Ethernet ring in accordance with the first and second correspondence information. 
   
     
     
         12 . A fault handling method for a communication network comprising a plurality of Ethernet rings, each Ethernet ring intersecting one or more neighbouring Ethernet rings at a respective shared link connecting at least two shared nodes, each of the plurality of Ethernet rings including a respective master node and one or more transit nodes, and each Ethernet ring being identified by a ring sequence number, the method comprising:
 a shared node of a shared link notifying a master node in a first notification of a fault detected at said shared link, said master node belonging to an Ethernet ring identified by the highest ring sequence number amongst a plurality of intersecting Ethernet rings sharing said shared link;   said master node joining, upon receiving said first notification, each of said plurality of intersecting Ethernet rings at said shared link as a transit node of said plurality of intersecting Ethernet rings;   said master node notifying, in a second notification, the one or more transit nodes of said Ethernet ring identified by the highest sequence number to join said plurality of intersecting Ethernet rings; and   said one or more transit nodes joining said plurality of intersecting Ethernet rings upon receiving said second notification.   
     
     
         13 . A communication device for implementation in an Ethernet ring, said Ethernet ring being one of a plurality of intersecting Ethernet rings in a communication network, the device including a primary port and a secondary port that is blocked from receiving data, the device comprising:
 a ring-extension module configured to: determine a fault in a shared link at which said Ethernet ring intersects a neighbouring Ethernet ring, unblock said secondary port to allow data to be received, configure the device to join said neighbouring Ethernet ring, and send a first notification in said Ethernet ring; and   a ring-recovery module configured to: determine said shared link is restored, block said secondary port from receiving data, configure the device to leave said neighbouring Ethernet ring, and send a second notification in said Ethernet ring.   
     
     
         14 . A communication device for implementation in an Ethernet ring, said Ethernet ring being one of a plurality of intersecting Ethernet rings in a communication network, the device comprising:
 a ring-extension module configured to: receive a first notification from said Ethernet ring, said first notification containing information of a neighbouring Ethernet ring intersecting said Ethernet ring at a shared link, and configure the device to join said neighbouring Ethernet ring in accordance with said first notification; and   a ring-recovery module configured to: receive a second notification from said Ethernet ring, said second notification containing information of said neighbouring Ethernet ring, and configure the device to leave said neighbouring Ethernet ring in accordance with said second notification.   
     
     
         15 . The communication device of  claim 13  wherein the device is provided at said shared link, and includes an extension port that connects to said Ethernet ring, and wherein
 said ring-extension module is further configured to send a third notification in said Ethernet ring in response to a detection of a fault in said shared link; and 
 said ring-recovery module is further configured to send a fourth notification in said Ethernet ring in response to a detection that said shared link is restored, and to block said extension port from sending/receiving data until a COMPLETE-FLUSH FDB message is received, whereupon said extension port is unblocked. 
 
     
     
         16 . The communication device of  claim 13  wherein each Ethernet ring is identified by a ring sequence number, said neighbouring Ethernet ring being identified by a lower ring sequence number than said Ethernet ring, and wherein said first notification and said second notification each contains the ring sequence number of said Ethernet ring and the ring sequence number of said neighbouring Ethernet ring.